A lot of websites that allow ones to create buttons offer the possibility to create buttons with magnets on the back instead of the usual pin. It's better for the clothes as it doesn't require to make a hole in them.
I'm very VERY interested in that kind of products and I feel like it would be a great plusfor Sticker Mule (also I would not have to order on another website while I'd love to do it here ;)).
Cheers.